1. Field of the Invention:
The invention relates generally to attic insulation and more particularly to a covering for a pull-down staircase to prevent drafts and provide thermal insulation over the staircase without interfering with the operation of the staircase itself. The present application claims the benefit of provisional application U. S. Ser. No. 60/005,806 filed Oct. 23, 1995.
2. Discussion of Background:
The importance of energy conservation was underscored in the 1970's when the price of oil and related fuels increased dramatically. As a consequence, many homeowners made changes to the way they used energy in their homes, and new homes were built with greater emphasis on energy usage. Turning down a thermostat in winter and up in summer, adding insulation to ceilings and walls and installing better windows make a big difference in energy consumption for space heating and cooling. After these three measures, however, it becomes more and more difficult to reduce energy consumption economically without increasing discomfort for those who occupy the space.
Additional energy savings can be obtained, of course, but often only with a financial investment that rivals the reduced energy costs. In some cases, the homeowner must wait a number of years to be paid back for that investment by those lowered energy bills. In a few cases, it is better to forego, at least for a time, the installation of energy saving equipment. For example, more efficient appliances can be installed, but it is often diseconomic to do so before the appliances in the home have approached their full, useful life. Thus, the "payback time" or the time that is required for a homeowner to use a product that saves energy before he can recoup his investment in that product is a factor in deciding which products to buy and whether to buy them at all. The longer the payback time, the less desirable the product from an energy savings standpoint.
It is not uncommon for there to be ample insulation in an attic floor, with an R value of 30 or higher, and to have little or no insulation at the point where the pull-down stairs are installed. Not only is the insulation at that location often limited to the materials the staircase is made of, but there can be leakage of air around the staircase between the rooms below and the attic above. This problem has been addressed before, and there are a number of devices that cover the pull-down stairs to an attic to add insulation to the staircase. However, many of these are complicated affairs that are difficult to install or are expensive to manufacture, resulting in a disincentive to the busy homeowner because of a long payback time. Furthermore, the dominant characteristic of heat loss does not result from a lack of insulation in the attic near or over the stair case, but rather from air leaks to and from the attic. Therefore, the primary thrust of the present invention is its ability to provide an effective seal against drafts in a device having a very short payback time because of its exceptionally inexpensive, easy-to-install and convenient-to-ship system.
Known pull-down staircase covers are directed much more towards thermal insulation than leak insulation, and there are many different designs. For example, Edwards, in U.S. Pat. No. 4,151,894, teaches a box-like cover made of "wood, fiberglass or other suitable plastic" with a handle on the inside and a rubber gasket fixed to the lower edge of the cover to "sealingly engage the attic floor." An example of a compact attic staircase cover is found in Fuller's patent, U.S. Pat. No. 4,281,743, which breaks down into "nestable" parts for storage or shipping. The parts, preferably made of a foamed polymer such as polystyrene, have overlapping joints for better structural integrity.
Another simple cap-like cover is disclosed in U.S. Pat. No. 4,658,555 by Steiner. Steiner's cap is made of high R value materials, including a fiberglass "gasket" on the cap to seal it to the rough wood floor of the attic.
Helbig dimensions his enclosure to be shipped with the staircase, as taught by U.S. Pat. No. 4,312,423. However, in an alternative embodiment, he provides a second, redundant and larger enclosure over the first enclosure to cover the whole frame, not just the portion within the frame. The staircase cover designed by Daw, et al. in U.S. Pat. No. 4,832,153 has a compact storage arrangement of its various components, including two packaging pieces used simply to "shape" the overall set of components, all of which are made of fiberglass or rigid foam.
Some covers are attached at one side and rotate into a covering position. The simplest example is that disclosed by Waters, et al. in U.S. Pat. No. 4,344,505, who have a "door-like" hatch for a staircase made of expanded polystyrene. Another example of one of these is taught by Daley in U.S. Pat. No. 4,928,441. Daley also teaches the use of a sheet of sponge rubber attached to it that serves as a gasket between the upper part of the cover. Another example of a rotating dome-like cap for a pull-down staircase is seen in Mariano, et al., U.S. Pat. No. 4,550,543. Mariano, et al. teach the use of weather stripping adhered to the edge of a dome made of insulating material. Still another rotating cap for a staircase is provided by the teachings of Vesperman, et al. in U.S. Pat. No. 4,541,208 who set the sides of their fiberglass cover on rails, one of which permits limited rotation.
Characteristic of more elaborate closures is Hulligan's cover, described in U.S. Pat. No. 5,220,757. This enclosure remains in place during use of the staircase, but a flexible corrugated, plastic member pulls into position, in the manner of the cover of a roll-top desk, when the user wants to seal the attic. For other examples of more elaborate closures, see Sciambi, et al.'s closure in U.S. Pat. No. 4,591,022.
Finally, King teaches a zippered cover for an attic staircase in U.S. Pat. No. 4,337,602. His flexible cover is supported by posts along the sides.
All of the foregoing devices are designed to cover a pull-down staircase to prevent heat loss to the attic. Several also address drafts by applying a gasket or seal to the cover's edge that engages the attic floor or staircase frame. Most are either box-like or dome-like to accommodate the staircase when it is in the stored configuration. There are even some devices that address storage and shipping space. None, however, is made of a material that is thin enough to be folded into a truly compact shape for shipping and storage or applies the seal to the frame, rather than the edge of the cover. None has the economies that enables as rapid a payback as the present invention.